The present invention pertains generally to the field of lighting fixtures, and pertains more particularly to a process for manufacturing a generally toroidal ballast choke for use in such a fixture.
As is well known, lighting fixtures intended for use with fluorescent and other bulbs of types with which a ballast choke is used are frequently larger than those for incandescent bulbs of comparable bulk. It is often desirable to reduce the size of such fluorescent and similar fixtures as much as possible, whether to save space, or for reasons of economy or esthetics.
It would also be desirable to have a device by means of which fluorescent bulbs, etc., could be used with ordinary incandescent lamp sockets. Adapters designed for such use have been proposed, as have fluorescent lamps specifically designed for use in incandescent lamp fixtures. For example, U.S. Pat. No. 3,551,736 (Doehner) shows a fluorescent lamp in which a fluorescent bulb rests on a ballast unit and has electrical connector pins which extend through passages provided for them in the ballast unit. The ballast unit also receives electrical connector pins from a terminal contact base which is externally threaded to be screwed into a conventional incandescent lamp screw socket. In that patent, the ballast unit contains a toroidal ballast choke, with the connector pin passages extending through the hole of the torus. The starter and the capacitor are located in the screw base unit.
Conventional methods for manufacturing such devices are expensive because of the difficulty of mass-producing toroidal chokes, particularly because of the difficulty of forming a winding on a toroidal core.
It would be desirable to provide a convenient, simple, reliable and economical process for manufacturing a toroidal choke.